Modified catalyst supports

ABSTRACT

A modified catalyst support exhibiting attrition resistance and/or deaggregation resistance is provided. A catalyst composition including the modified catalyst support is also provided. A process to produce a modified catalyst support including treatment of a support slurry with a solution of monosilicic acid is provided. A process to use a catalyst including the modified catalyst support in a Fischer-Tropsch synthesis is provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Applicationentitled “Attrition Resistant Catalyst Supports” filed on Dec. 12, 2003,Ser. No. 60/529,310 the disclosure of which is incorporated herein byreference in its entirety.

FEDERALLY SPONSORED RESEARCH

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

FIELD OF THE INVENTION

The invention relates to modified catalyst supports showing attritionresistance, and/or, deaggregation-resistance, and/or regenerability. Theinvention further relates to a process to produce modified catalystsupports. The invention further relates to the use of Fischer-Tropschcatalysts including attrition-resistant catalyst, and/or,deaggregation-resistant, and/or regenerable supports in Fischer-Tropschsynthesis.

BACKGROUND OF THE INVENTION

Supported catalysts used in Fischer-Tropsch reactors, including forexample, slurry bubble column reactors and continuously stirred tankreactors (“CSTR”), are subjected to agitation causing significantcollisions and frictional forces. Such collisions and forces can resultin damage mechanisms which, over time, may cause attrition of thecatalyst and/or catalyst support. Attrition of catalyst and/or catalystsupport raises operating costs due to increased catalyst requirements.Moreover, attrition results in the production of fines which must beremoved by filtration. The filtration process may cause loss of activecatalyst in addition to removal of the fines, thereby further raisingoperating costs.

Catalyst supports used in fixed bed reactors may also be subjected tomovement and collisions during batch or continuous regenerationprocesses. Consequently, some attrition may occur with fixed bedreactors. Moreover, catalyst supports, such as shaped extrudates,frequently show appreciable attrition during catalyst production, e.g.cobalt deposition onto the support. In such instances, the attritedfines must be removed from the catalyst product prior to use to preventreactor plugging.

Attempts to reduce catalyst attrition include non-aqueous processes.Such processes require use of a non-aqueous solvent because thesilicating agent used reacts rapidly with water which would displace thedesired reaction of the silicate, with the hydroxyl or oxide groups onor near the surface of the catalyst support.

Yet another known process uses ethanol, i.e. non-aqueous, solutions oftetraethoxysilicate to deposit silicon onto catalyst supports for thepurpose of suppressing the solubility of the support in aqueous acidicsolutions which are typically encountered during preparation of thesupported catalyst.

However, the use of non-aqueous solvents raises costs due to the cost ofthe solvents themselves as well as the cost of specialized equipment.

SUMMARY OF THE INVENTION

Some embodiments of the invention provide a catalyst compositioncomprising a support material having between about 0.1 Si/nm² supportsurface area and about 10.6 Si/nm² support surface area depositedthereon wherein the Si atoms are bound directly to the support materialthrough an oxygen atom.

Other embodiments of the invention provide a catalyst compositioncomprising a support material having between about 0.1 Si/nm² supportsurface area and about 10.6 Si/nm² support surface area depositedthereon wherein less than about 10 wt % of the silicon is in polymericform.

Yet other embodiments of the invention provide a method of treating acatalyst support, comprising: contacting a support material with anattrition-suppressing composition comprising monosilicic acid thereby toprovide a treated catalyst support.

Yet other embodiments of the invention provide a catalyst compositionsuitable for use in a Fischer-Tropsch process, comprising a mixture orreaction product of: an attrition-resistant support prepared bycontacting a support material with an attrition-suppressing compositioncomprising monosilicic acid; a catalyst precursor composition comprisingcobalt, a first modifier selected from the group of Ca, Sc, Ba, La, Hf,and combinations thereof; and at least one activator selected from thegroup of Ru, Rh, Pd, Re, Ir, Pt, and combinations thereof.

Yet other embodiments of the invention provide a Fischer-Tropschproduct, comprising: a paraffinic wax; and less than about 50 ppm ofgamma alumina particles having a diameter of less than about 20 nm;wherein the concentration of gamma alumina particles is determinedfollowing primary filtration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of cumulative volume percent by particle size for anuntreated support and for a first treated support before and afterultrasonic treatments.

FIG. 2 is a graph of cumulative volume percent by particle size for anuntreated support and for a second treated support before and afterultrasonic treatments.

FIG. 3 is a graph of cumulative volume percent by particle size for anuntreated support before and following ultrasonic treatment.

FIG. 4 is a chart showing the properties of the catalysts discussed inExamples 1-10.

FIG. 5 is a graph showing ratio of Si to Al XPS intensity.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The term “support” means any pre-formed inorganic support materialhaving accessible hydroxyl and/or oxide groups and having penetrablepores. Supports, as used herein, may have any shape. The pores generallyhave openings greater than about 5 nm across the largest axis.

The term “pre-formed” means a catalyst support which is formed,including for example extraction, washing, drying, and setting theparticle size, prior to treatment with silicon compound and impregnationof an active metal, such as Group VIII metals. Catalyst supportsincluded in the term “pre-formed” include, for example, spray dried,extruded, and pelletized supports.

The term “Fischer-Tropsch product” means the aggregate composition ofhydrocarbons formed from synthesis gas by the FT synthesis process andremaining within the synthesis reactor vessel as a liquid at processconditions.

The term “primary filtration” means filtration of the Fischer-Tropschproduct as it passes from the FT reactor and removing particles greaterthan about 5 μm.

The term “paraffinic wax” means a hydrocarbon consisting predominatelyof unbranched —CH— chains which are semi-solid to solid at roomtemperature and pressure.

The term “directly bound to a support material through an oxygen atom”means attachment through one or more single bonds to one or more oxygenatoms, each oxygen atom singly bonded to the metal of the supportmaterial.

In some embodiments of the process of the invention, monosilicic acid(“MSA”) is prepared in accordance with the teachings of U.S. Pat. No.2,588,389, incorporated herein and made a part hereof. In preferredembodiments of the invention, the MSA is made under conditions whichminimize polymerization of the MSA. Such conditions are known in the artand examples of such conditions are discussed in the above citedreference. In some embodiments of the invention, the MSA is formed froma precursor at pHs between about 1.5 and about 3.5 and at temperaturesbetween about 0° C. and about 5° C. In some embodiments, the MSA isformed from a precursor at a temperature of up to about 25° C. Inpreferred embodiments, the MSA is formed from a precursor at atemperature between about 0° and about 8° C.; in a most preferredembodiment, the MSA is formed from a precursor at a temperature betweenabout 0° C. and about 5° C. The precursor may be any aqueous solution ofa silicate, including sodium silicates such as sodium orthosilicate andsodium metasilicate. The MSA solution generally contains between about0.1% to about 1.0% Si to total solution by weight. Following formationof the MSA, the MSA solution is preferably contacted with the supportwithin as short a time as is practicable. The MSA is very reactive,readily forming polymers by reaction with itself or alternatively,reacting with other oxidized surfaces, such as the surfaces of typicalcatalyst supports. The contacting of the MSA and catalyst support mayoccur by batch mixing or by metered addition of the MSA solution to anaqueous suspension of the support material. When batch mixing is used,the support solution is generally vigorously stirred during MSA additionto maximize contact between the MSA and support particles. When meteredaddition is used, the MSA is added at a rate which minimizesself-polymerization and favors reaction between the MSA and the supportby maintaining a relatively low concentration of unreacted MSA to totalsolution. Nevertheless, the reaction between the MSA and some catalystsupports, such as alumina, may be faster than MSA self-polymerization.In such cases, about a monolayer of the silicon may be readily depositedon the support particles even where batch addition of the MSA is usedand higher MSA concentrations in the mixture occur. The MSA and supportmixture may be stirred, preferably vigorously stirred, during and/orfollowing mixing to promote contact between the MSA and the surface ofthe support particles. In preferred embodiments of the invention, theamount of water used to form the aqueous suspension of the supportmaterial is minimized, with only an amount necessary to permit vigorousstirring to be used. Such amount of water will vary according to type,size and shape of support used. Generally, the MSA solution may becontacted with the support for a period of between about 1 minute toover 2 hours before subsequent processing. The MSA solution may becontacted with the support at temperatures ranging from between about 0°C. and about 95° C.

When higher temperatures are used, the MSA reagent may be added to thesupport slurry at a higher rate due to a faster reaction rate betweenthe MSA and the support material. Furthermore, even at a temperaturebelow 5° C., the MSA reagent exhibits some self-polymerization. Evenwith some degree of MSA self-polymerization, the active agent in the MSAreagent/support slurry mixture appears to be predominantly the monomericform of silicic acid. Relatively rapid hydrolysis, i.e.,depolymerization, of low polymers of MSA has been observed at lowunreacted MSA concentrations. Even at the end of the MSA addition, wherethe concentration of unreacted silicate climbs to about 500 ppm in themixture, there is a preponderance of the active monomer.

Following binding of the MSA onto the support, the mixture may becooled, excess solution may be decanted, and the treated support washedwith water to remove excess acid. The decant-wash cycle may be repeated.Following the final decanting, the remaining dense slurry may befiltered prior to drying and calcining. The slurry is then driedfollowed by calcining at temperatures ranging from about 400° C. toabout 800° C. and preferably at about 600° C.

The filter pore size used will be generally dependent upon support sizeand shape. Indeed, the dense slurry need not be filtered but rather maybe subjected to any of a number of known techniques for dewatering denseslurries. For example, the dense slurry may be centrifuged. Typically,the treated support material is dried at temperatures between about 100°C. to about 200° C., preferably at about 150° C. until the materialbecomes flowable. It will be understood that in commercial operations,the dewatered slurry may be dried and calcined continuously with a frontportion of a calcining zone acting as a drier by adjustment oftemperature ramp and flow rate. In most applications, the support willbe maintained at the calcining temperature for at least about one hour.

The terms “support(s)” and “support material(s)” are usedinterchangeably herein. Supports useful in the invention include anypreformed, inorganic particles having any shape, including for examplesubstantially spherical or extrudates, having accessible hydroxyl oroxide groups, and having pores penetrable as necessary for use in aFischer-Tropsch synthesis. Examples of suitable support materialsinclude, for example, alumina, including gamma, eta, theta, delta, andrho alumina, anatase and rutile titania, magnesia, zirconia or otherrefractory oxides selected from Groups III, IV, V, VI and VIII. Thesupport, prior to treatment according to the invention, may have adiameter or equivalent diameter ranging from about 0.025 mm to about 0.2mm. The amount of Si bound directly to the support material may rangefrom between about 0.77 Si/nm² to about 10.6 Si/nm².

As previously mentioned, monosilicic acid, Si(OH)₄, may undergoself-polymerization with the extent of polymerization dependent upontemperature, pressure and concentration of silicate. Consequently,preparation of practical solutions of silicic acid will contain not onlythe silicic acid monomer, but higher polymeric forms as well. Solutionsmost effective for the purposes of this invention will be composed ofthe lowest concentration of higher polymeric forms. For the purposes ofthis invention, a high quality solution includes a higher proportion ofmonomeric silicate than polymeric silicate. The quality of the solutionmay be characterized using a colorimetric determination based on theformation of aqueous silico-molybdate species as is know in the art.

The extent of MSA polymerization may be monitored by usingspectrophotometric techniques known in the art. One knownspectrophotometric method relies on the depolymerization of lowmolecular weight polymers of SiO₂ and the formation of silicomolybdicacid which has a yellow color. The reaction of Si(OH)₄ with molybdicacid is extremely rapid. The rate of formation of Si(OH)₄ is inverselyproportional to the length of the silicate polymer Therefore, the lowerthe degree of polymerization, the more rapidly the solution reaches itsfinal color intensity.

Several tests were made using this spectrophotometric technique in whichthe color change was monitored using a spectrophotometer set to 410 nm.MSA monomer achieved its final color in less than two minutes. The MSAcubic octomer requires more than ten minutes to reach its final colorand exhibits less than 50% of its final color in the first two minutes.Yet higher polymers require even longer to exhibit their final colorintensity and show a correspondingly lower fraction of their color attwo minutes or less. In some embodiments of the invention, the testsolutions achieved about 80% of their final color within two minutes andachieved their final color within six to ten minutes. Solutions weredeemed suitable for use when about >90% of the final color was developedwithin 5 minutes. In preferred embodiments of the invention, the testsolutions produced >90% of their color within 2 minutes, indicating veryhigh monomer content at the outset.

The treated support may be used for the preparation of a catalyst, suchas a Fischer-Tropsch catalyst. Any of a number of catalyst preparationmethods, for example impregnation of a Group VIII metal, are known inthe art and may be utilized with the treated support.

A Fischer-Tropsch catalyst incorporating the attrition-resistantcatalyst support of the invention includes a catalytically active amountof a catalytic metal, usually between about 1 wt % and 100 wt %,preferably between 2 wt % and 60 wt %, and most preferably between about10 wt % and about 30 wt %. Modifiers and/or activators may be includedin the catalyst composition and modifiers and activators useful inFischer-Tropsch catalysts are well known in the art. Activators include,for example, Ru, Rh, Pd, Re, Ir, Pt, and combinations thereof. Modifiersinclude, for example, Ca, Sc, Ba, La, Hf, and combinations thereof.Modifiers and/or activators are usually present in amounts less thanthat of the primary catalytic metal.

One typical catalyst preparation method utilizes impregnation byincipient wetness. For example, a cobalt nitrate salt may be impregnatedby incipient wetness onto a titania, silica, or alumina support,optionally followed by impregnation with a modifiers. The catalyst maythen be calcined at about 250° C. to about 500° C. to covert the metalsalt to its corresponding oxide. The oxide may then be reduced bytreatment with hydrogen or a hydrogen containing gas at about 300° C. toabout 500° C. for a time sufficient to substantially reduce the oxide tothe elemental or catalytic form of the metal. Other well known catalystpreparation methods are those disclosed in U.S. Pat. Nos. 4,673,993;4,717,702; 4,477,595; 4,663,305; 4,822,824; 5,036,032; 5,140,050;5,252,613; and 5,292,705, the disclosures of which are incorporatedherein by reference.

The supports treated as described herein display improved attritionresistance over untreated supports. One method for gauging the relativeattrition resistance of supports is based on the use of an ultrasonicprobe to produce conditions wherein the support particles collide withone another with a high frequency and sufficient energy to potentiallycause fracture of the support particles. Such test method is discussedin U.S. Pat. No. 6,262,132, which is incorporated herein by reference.FIG. 1 shows the results of such ultrasonic testing on a support, both afirst treated and untreated samples of such support. The curves in FIG.1 show the cumulative volume percent as a function of particle size forthese samples, before and after ultrasonic testing. Specifically, thecurve shown with diamond data points depicts the particle sizecumulative distribution of an untreated support before ultrasonictreatment; the curve shown with triangle data points depicts theparticle size cumulative distribution of a first treated support beforeultrasonic treatment; the curve shown with box data points depicts theparticle size cumulative distribution of an untreated support followingultrasonic treatment; the curve shown with “X” data points depicts theparticle size cumulative distribution of the first treated supportfollowing ultrasonic treatment. As can be seen from FIG. 1, theuntreated support shows a significantly greater shift to smallerparticle size following ultrasonic treatment than that displayed by thetreated support. The same trend is shown in FIG. 2 with the untreatedsupport following ultrasonic testing showing a significantly greatershift to smaller particle sizes than that of a second treated supportfollowing ultrasonic testing. The support material used in the examplesshown in FIGS. 1 and 2 are the same material but separate samples ofsuch material. The untreated sample is the same in both FIGS. 1 and 2.Referring to both FIGS. 1 and 2, the untreated supports followingultrasonic testing exhibit a population of particles smaller than 20microns in diameter. While the treated supports following ultrasonictesting also exhibit particles having diameters (or effective diameters)of less than 20 microns, the sub-20 micron population in the treatedsupport is about one-half that seen in the untreated supports. Moreover,the overall shift to smaller particle sizes is also less for the treatedsupports than for the untreated supports.

The ultrasonic testing discussed above was completed on an untreatedsupport sample and the cumulative volume percent vs. particle size ofsuch sample before and after ultrasonic testing is shown in FIG. 3. Thecumulative volume percent vs. particle size was then remeasured for theuntreated sample subjected to ultrasonic testing after about six months.The particle size distribution remains substantially identical to thatmeasured in the earlier testing thereby demonstrating that theultrasonic test is highly rigorous with excellent reproducibility.

In addition to attrited catalyst particles, it has been observed thatFischer-Tropsch product waxes may also contain particulatessignificantly smaller in size than attrition products. NMR analysis ofthese particulates, according to known methods, shows these solids to becomprised substantially of gamma alumina crystallites. TEM analysis ofthese particulates, using known methods, shows that these solids have asize of less than about 20 nm along any crystalline axis. Such gammaalumina crystallites are believed to be deaggregated fragments from thecatalyst particles. Because the deaggregated gamma alumina fragments aresignificantly smaller in size than attrition products, the deaggregatedgamma alumina may be separated from the attrition products. Thecomposition of the deaggregated gamma alumina product differs from thecomposition of the original catalyst. Whereas the catalyst typically hasa composition of about 20 wt % elemental cobalt, and 70 wt % Al₂O₃, thedeaggregated gamma alumina product are depleted of cobalt, typicallycontaining about 3 wt % to about 4 wt % elemental Co and about 95 wt %Al₂O₃.

EXAMPLE 1 Preparation of Catalyst Sample 1

MSA reagent solution was prepared with 94.9 g TEOS rapidly added to 4 Lof acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. In a separate stirred, heatedvessel, a slurry of the alumina support containing 640 g aluminasuspended in 2 L of demineralized water was heated. The slurry was heldat 50°±5° C. throughout the addition of the MSA reagent, which was addedat a rate of 35 ml/min. Following completion of the MSA addition, theslurry was stirred and kept at 50°±5° C. until >95% of the silicon wasreacted with the alumina. Once reaction was complete, stirring wasstopped, the solids allowed to settle, and the clear mother liquordecanted from the vessel. The remaining dense slurry was vacuum filteredto remove the remainder of the solution. The filtered solid was spreadonto a drying tray to a thickness less than 1.5 cm and dried overnightin an oven held at 140° C. This dried powder was then calcined in a dishat 600° C. for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce an incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 187 g of a second charge of the saturated cobalt solution,1.8 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 2 Preparation of Catalyst Sample 2

MSA reagent solution was prepared with 73.6 g TEOS rapidly added to 667ml of acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. In a separate stirred, heatedvessel, a slurry of the alumina support containing 100 g aluminasuspended in 333 ml of demineralized water was heated. The slurry washeld at 50°±5° C. throughout the addition of the MSA reagent, which wasadded at a rate of 5 ml/min. Following completion of the MSA addition,the slurry was stirred and kept at 50°±5° C. until >95% of the siliconwas reacted with the alumina. Once reaction was complete, stirring wasstopped, the solids allowed to settle, and the clear mother liquordecanted from the vessel. The remaining dense slurry was vacuum filteredto remove the remainder of the solution. The filtered solid was spreadonto a drying tray to a thickness less than 1.5 cm and dried 6 h in astatic muffle furnace oven held at 140° C. This dried powder was thencalcined in a dish at 600° C. for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 93.8 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 87.6 g of this saturated Co solution was usedfor the first impregnation pass. 4.08 g of La(NO₃)₃.6H₂O were dissolvedin log of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce an incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 87.5 g of a second charge of the saturated cobalt solution,0.97 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 3 Preparation of Catalyst Sample 3

MSA reagent solution was prepared with 94.9 g TEOS rapidly added to 4 Lof acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. A slurry of the alumina supportcontaining 640 g alumina suspended in 2 L of demineralized water wasadded to the MSA. The mixture was then heated to 50°±5° C. The mixturewas stirred and kept at 50°±5° C. until >95% of the silicon was reactedwith the alumina. Once reaction was complete, stirring was stopped, thesolids allowed to settle, and the clear mother liquor decanted from thevessel. The remaining dense slurry was vacuum filtered to remove theremainder of the solution. The filtered solid was spread onto a dryingtray to a thickness less than 1.5 cm and dried overnight in an oven heldat 140° C. This dried powder was then calcined in a dish at 600° C. for4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 187 g of a second charge of the saturated cobalt solution,1.8 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 4 Preparation of Catalyst Sample 4

MSA reagent solution was prepared with 38 g TEOS rapidly added to 1.62 Lof acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. This MSA solution was kept coldand held for ˜60 hrs. A slurry of the alumina support containing 640 galumina suspended in 768 ml of demineralized water was added to the MSA.The mixture was then heated to 50°±5° C. The mixture was stirred andkept at 50°±5° C. until >95% of the silicon was reacted with thealumina. Once reaction was complete, stirring was stopped, the solidsallowed to settle, and the clear mother liquor decanted from the vessel.The remaining dense slurry was vacuum filtered to remove the remainderof the solution. The filtered solid was spread onto a drying tray to athickness less than 1.5 cm and dried overnight in an oven held at 140°C. This dried powder was then calcined in a dish at 600° C. for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 194 g of a second charge of the saturated cobalt solution,1.82 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 5 Preparation of Catalyst Sample 5

MSA reagent solution was prepared with 38 g TEOS rapidly added to 1.62 Lof acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. A slurry of the alumina supportcontaining 640 g alumina suspended in 768 ml of demineralized water wasadded to the MSA. The mixture was then heated to 50°±5° C. The mixturewas stirred and kept at 50°±5° C. until >95% of the silicon was reactedwith the alumina. Once reaction was complete, stirring was stopped, thesolids allowed to settle, and the clear mother liquor decanted from thevessel. The remaining dense slurry was vacuum filtered to remove theremainder of the solution. The filtered solid was spread onto a dryingtray to a thickness less than 1.5 cm and dried overnight in an oven heldat 140° C. This dried powder was then calcined in a dish at 600° C. for4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 192 g of a second charge of the saturated cobalt solution,1.82 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 6 Preparation of Catalyst Sample 6

MSA reagent solution was prepared with 94.9 g TEOS rapidly added to 4 Lof acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld at room temperature ˜22° C. 15 minutes after TEOS addition, analiquot was removed and the rate of color change tested. Greater than90% of the full color developed within 5 minutes. 640 g of alumina wasadded to the MSA. The mixture was then heated to 50°±5° C. The mixturewas stirred and kept at 50°±5° C. until >95% of the silicon was reactedwith the alumina. Once reaction was complete, stirring was stopped, thesolids allowed to settle, and the clear mother liquor decanted from thevessel. The remaining dense slurry was vacuum filtered to remove theremainder of the solution. The filtered solid was spread onto a dryingtray to a thickness less than 1.5 cm and dried overnight in an oven heldat 140° C. This dried powder was then calcined in a dish at 600° C. for4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 187 g of a second charge of the saturated cobalt solution,1.8 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 7 Preparation of Catalyst Sample 7

MSA reagent solution was prepared with 89.3 g TEOS rapidly added to 2 Lof acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. In a separate stirred, heatedvessel, a slurry of the alumina support containing 300 g aluminasuspended in 1 L of demineralized water was heated. The slurry was heldat 50°±5° C. throughout the addition of the MSA reagent, which was addedat a rate of 15 ml/min. Following completion of the MSA addition, theslurry was stirred and kept at 50°±5° C. until >95% of the silicon wasreacted with the alumina. Once reaction was complete, stirring wasstopped, the solids allowed to settle, and the clear mother liquordecanted from the vessel. The remaining dense slurry was vacuum filteredto remove the remainder of the solution. The filtered solid was spreadonto a drying tray to a thickness less than 1.5 cm and dried 6 h in astatic muffle furnace held at 140° C. This dried powder was thencalcined in a dish at 600° C. for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 185 g of a second charge of the saturated cobalt solution,1.78 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 8 Preparation of Catalyst Sample 8

MSA reagent solution was prepared with 68 g TEOS rapidly added to 2 L ofacidified demineralized water under vigorous stirring. Sufficient HNO₃was added to the water to bring the pH to between 2.2 and 2.5 and heldbetween 3° C. and 8° C. 15 minutes after TEOS addition, an aliquot wasremoved and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. In a separate stirred, heatedvessel, a slurry of the alumina support containing 300 g aluminasuspended in 1 L of demineralized water was heated. The slurry was heldat 50°±5° C. throughout the addition of the MSA reagent, which was addedat a rate of 15 ml/min. Following completion of the MSA addition, theslurry was stirred and kept at 50°±5° C. until >95% of the silicon wasreacted with the alumina. Once reaction was complete, stirring wasstopped, the solids allowed to settle, and the clear mother liquordecanted from the vessel. The remaining dense slurry was vacuum filteredto remove the remainder of the solution. The filtered solid was spreadonto a drying tray to a thickness less than 1.5 cm and dried 6 h in astatic muffle furnace held at 140° C. This dried powder was thencalcined in a dish at 600° C. for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 188 g of a second charge of the saturated cobalt solution,1.78 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 9 Preparation of Catalyst Sample 9

MSA reagent solution was prepared with 27.8 g TEOS rapidly added to 1.33L of acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. This MSA solution was kept coldand held for 60 hrs. In a separate stirred, heated vessel, a slurry ofthe alumina support containing 200 g alumina suspended in 667 ml ofdemineralized water was heated. The slurry was held at 50°±5° C.throughout the addition of the aged MSA reagent, which was added at arate of 15 ml/min. The mixture was stirred and kept at 50°±5° C.until >95% of the silicon was reacted with the alumina. Once reactionwas complete, stirring was stopped, the solids allowed to settle, andthe clear mother liquor decanted from the vessel. The remaining denseslurry was vacuum filtered to remove the remainder of the solution. Thefiltered solid was spread onto a drying tray to a thickness less than1.5 cm and dried 6 h in a static muffle furnace held at 140° C. Thisdried powder was then calcined in a dish at 600° C. for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 160 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 138 g of this saturated Co solution was usedfor the first impregnation pass. 5.00 g of La(NO₃)₃.6H₂O were dissolvedin 15 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 151 g of a second charge of the saturated cobalt solution,1.44 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

EXAMPLE 10 Preparation of Catalyst Sample 10

MSA reagent solution was prepared with 29.8 g TEOS rapidly added to 267ml of acidified demineralized water under vigorous stirring. SufficientHNO₃ was added to the water to bring the pH to between 2.2 and 2.5 andheld between 3° C. and 8° C. 15 minutes after TEOS addition, an aliquotwas removed and the rate of color change tested. Greater than 90% of thefull color developed within 5 minutes. In a separate stirred, heatedvessel, a slurry of the alumina support containing 200 g aluminasuspended in 667 ml of demineralized water was heated. The slurry washeld at 50°±5° C. throughout the addition of the MSA reagent, which wasadded at a rate of 15 ml/min. Following completion of the MSA addition,the slurry was stirred and kept at 50°±5° C. until >95% of the siliconwas reacted with the alumina. Once reaction was complete, stirring wasstopped, the solids allowed to settle, and the clear mother liquordecanted from the vessel. The remaining dense slurry was vacuum filteredto remove the remainder of the solution. The filtered solid was spreadonto a drying tray to a thickness less than 1.5 cm and dried 6 h in astatic muffle furnace held at 140° C. This dried powder was thencalcined in a dish at 600° C. for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 200 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 172.5 g of this saturated Co solution was usedfor the first impregnation pass. 6.25 g of La(NO₃)₃.6H₂O were dissolvedin 20 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce and incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 184 g of a second charge of the saturated cobalt solution,1.78 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

The catalysts produced in examples 1-10 were examined for attritionresistance according to the following method. The catalyst was activatedusing hydrogen gas and 20 cc of the activated catalyst are loaded into a0.5 L CSTR and brought to synthesis conditions at 410° F., 300 psi, GHSV8000/hr and a stirrer speed of 1000 rpm. After 50 hours of synthesisoperation, conditions are adjusted to 420° F., 400 psi, GHSV 8000/hr anda stirrer speed of 2000 rpm. This condition is maintained for 150 hours.At the completion of a CSTR attrition test, the reactor is switched to anitrogen purge and cooled to about 250° F. It is held under theseconditions for about 24 hours, during which time whole catalyst andlarger attrition fragments settle to the bottom of the reactor but fineattrition fragments remain suspended in the wax. The wax is then cooleduntil solid and removed from the reactor as a single plug. Thecatalyst-containing wax plug of the settled fraction can be separatedfrom the overhead wax which contains the unsettled, smallerattrition-produced catalyst fragments. Once separated, the overhead waxfraction is granulated and homogenized after which a representativesample is taken. This representative fraction is placed into a pyrexbeaker, placed into an oven held at between about 280 to about 320° F.and allowed to melt. A pyrex filtration system with a vacuum receiver isalso heated to the oven temperature. The wax is filtered first through a5 μm filter, the collected liquid then filtered through a 0.45 μmfilter, with the collected liquid filtered a final time through a 0.1 μmfilter. At each stage of filtration, a small amount of clean isoparsolvent is used to sweep all of the material from the bottom of thevessel. At the conclusion of filtration, the filtrate residual solidscontent is determined by ashing. The filtered solids are separated fromthe filter papers using a solvent in an ultrasonic bath. Thesolids-bearing solvent is centrifuged to concentrate the solids whichare finally collected, dried, and weighed. These masses are referencedto the original mass of catalyst loaded into the reactor and the resultsare shown in the Table contained in FIG. 4.

EXAMPLE 11 Reaction of MSA with Alumina

667 ml of demineralized water was acidified with HNO₃ to pH=2.0 andcooled to less than 8° C. with an ice bath. 74.63 g of TEOS were addedto the acidified water with vigorous stirring. The rate of color changewas tested after 15 minutes of mixing and showed >90% of maximum colorwithin 5 minutes. In a separate vessel, 333 ml of demineralized waterwere combined with 100 g of Sasol Chemical SCCa-30/140 alumina andheated to 50° C. while mixing with an overhead mixer. The silicic acidreagent was added to the alumina slurry using a peristaltic pump over aperiod of 135 minutes. After three hours of mixing, the amount ofunreacted silcic acid was found to be 35% of the initial charge. Caremust be taken in this measurement to allow for the depolymerization ofsomewhat larger polymers of silicic acid. This higher degree ofpolymerization is brought about by the higher concentration of unreactedsilicic acid, elevated temperature, and shift of pH from the point ofoptimal stability in this saturation preparation. The resultingdeposition was self-limiting to about 5.7% Si on the calcined alumina.

COMPARATIVE EXAMPLE 1 Reaction of MSA with Silica

667 ml of demineralized water was acidified with HNO₃ to pH=2.0 andcooled to less than 8° C. with an ice bath. 13.9 g of TEOS was added tothe acidified water with vigorous stirring. The rate of color change wastested after 15 minutes of mixing and showed >90% of maximum colorwithin 5 minutes. In a separate vessel, 333 ml of demineralized waterwas combined with 10 g of silica gel (Davisil Grade 64b type 150a,available from Davison Catalysts) and heated to 50° C. while mixing withan overhead mixer. A background test of silicic acid formed in theslurry was done using the molybdate color change test. The silicic acidreagent was added to the silica slurry using a peristaltic pump over aperiod of 60 minutes. A first test of unreacted silica was done afterone hour of mixing. From this test, it was determined that thebackground color change from the silica in water slurry contributed lessthan 5% of the total color change at that point. The amount of unreactedsilicic acid remaining was determined hourly for a total of three hours,at which point 75% of the silicic acid remained unreacted in thesolution. This resulting deposition was self-limiting to less than 0.5%Si on the calcined silica.

COMPARATIVE EXAMPLE 2 Reaction of MSA with Titania

667 ml of demineralized water was acidified with HNO₃ to pH=2.0 andcooled to less than 8° C. with an ice bath. 13.9 g of TEOS were added tothe acidified water with vigorous stirring. The rate of color change wastested after 15 minutes of mixing and showed >90% of maximum colorwithin 5 minutes. In a separate vessel, 333 ml of demineralized waterwas combined with 100 g of titania (Titania Type P-25, available fromDegussa AG) and heated to 50° C. while mixing with an overhead mixer.The silicic acid reagent was added to the titania slurry using aperistaltic pump over a period of 60 minutes. A first test of unreactedsilica was done after one hour of mixing, indicating 57% of the silicicacid remained unreacted. After three hours of mixing, the amount ofunreacted silicic acid was found to be 36% of the original charge. Thisresulting deposition was self-limiting to slightly under 1% Si on thecalcined titania.

COMPARATIVE EXAMPLE 3 AND EXAMPLE 11A Deaggregated Gamma Alumina

A semiworks batch of catalyst, Example 11A, was prepared on a SasolChemical SCCa-30/140 alumina which had been modified to contain 3.0Si/nm². A semiworks batch of catalyst, Comparative Example 3, wasprepared on an unmodified Sasol Chemical SCCa-30/140 alumina. Example11A was run in a proprietary Fischer-Tropsch synthesis in a 36 inchslurry bubble column reactor. Three runs using Comparative Example 3were made, one each in 42 inch, 36 inch, and 6 inch slurry bubblecolumns using a prorpietary Fischer-Tropsch synthesis. Wax samples wereobtained at the filtered product outlet and analyzed for deaggregatedalumina at comparable time on stream of 45 days. The results are givenin Table 1 below. The deaggregated gamma alumina particles wereseparated from other Fischer-Tropsch catalyst attrition solids using aprogressive filtration method. The wax sample is placed into a pyrexbeaker, placed into an oven held at between about 280 and about 320° F.and allowed to melt. A pyrex filtration system with a vacuum receiver isalso heated to oven temperature. The melted wax is subjected to a seriesof progressive filtrations using 5 μm, 0.45 μm, and 0.1 μm pass filters,sequentially. A final filtration is done using an Anodisc aluminum oxidefilter membrane with a pass size of 0.02 μm. At each stage offiltration, a small amount of clean isopar solvent is used to sweep allof the material from the bottom of the vessel. The final filtrate isthen ashed according to ASTM-486 and the deaggregated particulatecontent determined. TABLE 1 Deaggregate Sample Reactor ParticulatesComparative Example 3 42 inch 1700 ppm Comparative Example 3 36 inch 700 ppm Comparative Example 3  6 inch 1400 ppm Example 11A 36 inch  <10ppm

EXAMPLE 12 Distribution of Si within the Alumina Beads

Alumina support obtained from Sasol Chemical sold under the designationSCCa-30/140 is a spray-dried material consisting of spheroidal particlesbetween 25 μm and 100 μm in diameter. To determine the profile of the Siwithin or on the support particles after treatment with the monosilicicacid reagent, samples of modified support were embedded in a polymermatrix mounted to a microscope slide and polished so as to revealexposed cross-sections of whole particles. The polished slide was thenexamined with an SEM and sections along the diameter of several beadsanalyzed using energy dispersive X-ray analysis. When measured acrossmany beads of different diameter, the Si/Al signal ratio was found tovary by roughly 10%, approximately consistent with the expectedvariability of the technique. Slightly higher Si/Al ratios, byapproximately 15%, based on the average of several interior points onseveral beads, were observed at the extreme exterior edge of the beads.From these observations we conclude that the rate of reaction betweenthe monosilicic acid and the alumina surface is sufficiently slow toallow for the diffusion of the reagent to all points within the beads.

EXAMPLE 13 Surface Si Enrichment in Polymerized Silicic Acid Reagent

The supports produced by the methods of examples 4 and 5, prior to anyfurther treatment to form the catalyst particles, were analyzed usingX-ray photoelectron spectroscopy (XPS). Each of the supports of examples4 and 5 were modified to give 0.8% Si on the calcined support. Themodified support of example 5 was prepared immediately upon preparationof the MSA reagent whereas the MSA used to produce the modified supportof example 4 was first aged about 60 hours before reacting it with thealumina support. The rate of color change of the aged solution used toprepare the modified support of example 4 indicated that the silica hadpolymerized to a very high degree. XPS is extremely surface sensitive,providing information about the superficial surface in a layer roughly 5nm deep. The catalyst beads were examined without supplementalpreparation so as to restrict the analysis to only the true exteriorsurface of the beads. The Si/Al signal ratio was found to be 60% higherin the modified support of example 4 than in the modified support ofexample 5, indicating that the polymerized silicic acid was unable topenetrate the entire support particle before reacting with the alumina.As can be seen in the Table attached in FIG. 4, the modified supportexample 4 is less effective at mitigating attrition than the modifiedsupport of example 5.

EXAMPLE 14 Retained Attrition Resistance with Regeneration

200 g of Sasol Puralox SCCa-30/140 alumina was charged into a steamjacketed impregnation vessel. 37.04 g TEOS was added to 75 cc ethanol.The TEOS/EtOH mixture was added drop-wise to the alumina in theimpregnation vessel. The mixture was allowed to mix at ambienttemperature for 1 hour. Steam drying was started and continued for 3hours. The alumina mixture was cooled and then transferred to ceramiccalcining dishes. The alumina bed depth was <1.5 cm. The alumina was putinto a static muffle furnace and ramped to 140° C. over ˜30 mins. Thealumina was held for 2 hours at 140° C. This dried powder was thenramped to 600° C. and calcined for 4 hours. This support materialcontained 2.5 Si/nm².

Catalyst was prepared to have a nominal composition of 20% Co, 1% La,and 0.1% Ru in the calcined form. 10 g of the Si-modified catalystsupport were charged to a steam-jacketed, rotating impregnation vessel.A saturated solution prepared from Co(NO₃)₂.6H₂O and demineralized waterwas prepared in advance. 70.8 g of this saturated Co solution was usedfor the first impregnation pass. 3.13 g of La(NO₃)₃.6H₂O were dissolvedin 10 g of demineralized water and combined with the Co solution. Theamount of solution was selected so as to produce an incipiently wetpowder when applied to the support in the rotating vessel. Theimpregnated powder is allowed to tumble in the impregnator for one hourat ambient temperatures and then steamed to dryness over a three hourperiod. The powder is cooled to ambient, weighed, and transferred toshallow calcining dishes such that the powder depth is ≦2 cm. The dishesare placed into an electrically heated oven which is ramped from ambientto 120° C., held at 120° C. for 2 hours, ramped to 350° C. over a twohour period and held at 350° C. for an additional 2 hours. After coolingto ambient, the calcined powder is again transferred to the impregnationvessel. To 106.7 g of a second charge of the saturated cobalt solution,0.9 g of a 13.5% Ru solution of Ru(NO)(NO₃)₃ is added. This secondimpregnation solution is again applied to the substrate in the tumblingimpregnator and dried and calcined as following the first pass.

An initial 80 cc charge of catalyst prepared on a support treated withTEOS/EtOH, as described above in this Example, was run in a 1 liter CSTRunder typical FT synthesis conditions, adjusting temperature and GHSV inorder to maintain conversion above 55%. Following an initial operatingperiod of 2000 hours, the catalyst was regenerated in accordance withprocedures described in U.S. Pat. No. 6,812,179, the disclosure of whichis incorporated herein by reference. The regenerated charge was againoperated for 2000 hours and again regenerated. Following a thirdoperating period of 2000 hours, the catalyst was recovered, dewaxed, andthe particle size distribution measured. The initially loaded catalysthad a distribution with >99% of the particles larger than 20 μm indiameter. After the 6000 operating hours and 2 regenerations, therecovered catalyst still exhibited no detectable fines, still with >99%of the particles larger than 20 μm.

An initial 80 cc charge of catalyst prepared on a support treated withMSA so as to deposit 3.0 Si/nm², was run in a 1 liter CSTR under typicalFT synthesis conditions, adjusting temperature and GHSV in order tomaintain conversion above 55%. Following an initial operating period of2000 hours, the catalyst was regenerated in accordance with proceduresdescribed in U.S. Pat. No. 6,812,179. The regenerated charge was againoperated for 2000 hours and again regenerated. Following a thirdoperating period of 1800 hours, the catalyst was recovered, dewaxed, andthe particle size distribution measured. The initially loaded catalysthad a distribution with >99% of the particles larger than 20 μm indiameter. After the 5800 operating hours and 2 regenerations, therecovered catalyst still exhibited no detectable fines, with >99% of theparticles larger than 20 μm.

EXAMPLE 15 Preparation of Catalyst Sample 15 (TEOS/EtOH Method)

350 g of Sasol SCCa-30/140 alumina was charged into a steam jacketedimpregnation vessel. 25.9 g TEOS was added to 168 cc ethanol. TheTEOS/EtOH mixture was added drop-wise to the alumina in the impregnationvessel. The mixture was allowed to mix at ambient temperature for 1hour. Steam drying was started and continued for 3 hours. The aluminamixture was cooled and then transferred to ceramic calcining dishes. Thealumina bed depth was <1.5 cm. The alumina was put into a static mufflefurnace and ramped to 140° C. over ˜30 mins. The alumina was held for 2hours at 140° C. This dried powder was then ramped to 600° C. andcalcined for 4 hours.

Catalyst was prepared to have a nominal composition of 20% Co and 0.1%Ru in the calcined form. 200 g of the Si-modified catalyst support werecharged to a steam-jacketed, rotating impregnation vessel. A saturatedsolution prepared from Co(NO₃)₂.6H₂O and demineralized water wasprepared in advance. 172.45 g of this saturated Co solution was used forthe first impregnation pass. The amount of solution was selected so asto produce an incipiently wet powder when applied to the support in therotating vessel. The impregnated powder is allowed to tumble in theimpregnator for one hour at ambient temperatures and then steamed todryness over a three hour period. The powder is cooled to ambient,weighed, and transferred to shallow calcining dishes such that thepowder depth is ≦2 cm. The dishes are placed into an electrically heatedoven which is ramped from ambient to 120° C., held at 120° C. for 2hours, ramped to 350° C. over a two hour period and held at 350° C. foran additional 2 hours. After cooling to ambient, the calcined powder isagain transferred to the impregnation vessel. To 176.67 g of a secondcharge of the saturated cobalt solution, 1.75 g of a 13.5% Ru solutionof Ru(NO)(NO₃)₃ is added. This second impregnation solution is againapplied to the substrate in the tumbling impregnator and dried andcalcined as following the first pass.

EXAMPLE 16 Dispersion of Si on the Alumina Surface Through XPS

Since the silicic acid is prone to polymerize, a question arises as tothe possibility that higher oligomers begin to form as the concentrationof Si on the alumina surface is increased. X-ray photoelectronspectroscopy (XPS) can be used to address this question. Since thesignal observed by XPS derives from the outermost surface exposed to theexcitation X-ray beam, usually 3-5 nm in depth, it is well suited todetect such changes in morphology. Even in the event that a single layerstructure converts to a two layer structure, the second layer signalwill be attenuated relative to the signal from the first layer.Consequently, a ratio of the observed Si/Al ratio as a function ofsurface coverage should show a deviation toward diminishing Si/Aldetected as layered structures form, even if these layered structuresare islands and not contiguous surfaces.

Since XPS is so superficial surface sensitive, the interior surfaces ofthe support needs to be made available for analysis. This wasaccomplished through mechanical grinding of the calcined supportsfollowed by sieving through a 20 μm opening sieve. Particles fracturedto be smaller than this dimension must expose a relatively highproportion of interior surface.

FIG. 5 shows the change in Si/Al ratio observed for samples with nominalSi loadings ranging from 0.3 Si/nm² through 6.2 Si/nm². The high degreeof linearity clearly indicates that the morphology of the SiO₂ entitiesformed at the lowest, 0.3 Si/nm², Si concentration are the same as thoseformed at the highest concentration, 6.2 Si/nm². These observationsindicate that the SiO₂ deposited most likely binds as individualentities in a single layer on the Al₂O₃ surface.

EXAMPLE 17 Textural Evidence for Uniform Deposition

Nitrogen adsorption can be used to monitor changes in surface area, porevolume, and average pore diameter as a function of Si loading onto thealumina surface. In the event that polymeric entities begin to form,blockage of pores can occur, resulting in a discontinuous change in porevolume with increased loading. Similarly, blockages change the effectiveaverage pore diameter. The following table shows the textural dataobtained at several different nominal Si loadings. All three texturalparameters show continuous behavior, particularly the average porediameter, consistent with a continuous deposition of SiO₂ onto thealumina surface. BJH Desorption BJH Desorption Surface N₂ Pore AveragePore Area m²/g Volume (cc/g) Diameter (nm) Sample 140.49 0.44 8.28unmodified 3.1 Si/nm²on 138.4 0.41 8.42 30/140 4.6 Si/nm²on 133.15 0.387.84 30/140 6.2 Si/nm²on 135.6 0.37 7.67 30/140 8.5 Si/nm²on 139.3 0.337.08 30/140 8.8 Si/nm²on 142.96 0.32 6.75 30/140

While the invention has been described with a limited number ofembodiments, these specific embodiments are not intended to limit thescope of the invention as otherwise described and claimed herein.Modification and variations from the described embodiments exist. Aperson of ordinary skill in the art recognizes parameters for theformation of semiconductor materials processes may vary, for example, intemperature, pressure, gas flow rates, and so on. Therefore, materialswhich do not fulfill the selection criteria under one set of processconditions may nevertheless be used in embodiments of the inventionunder another set of process conditions. The incorporation of additionalelements may result in beneficial properties which are not otherwiseavailable. Also, while the processes are described as comprising one ormore steps, it should be understood that these steps may be practiced inany order or sequence unless otherwise indicated. These steps may becombined or separated. Finally, any number disclosed herein should beconstrued to mean approximate, regardless of whether the word “about” or“approximate” is used in describing the number. The appended claimsintend to cover all such variations and modifications as falling withinthe scope of the invention.

1. A catalyst composition comprising: support material having betweenabout 0.1 Si/nm² support surface area and about 10.6 Si/nm² supportsurface area deposited thereon wherein the Si atoms are bound directlyto the support material through an oxygen atom.
 2. The catalystcomposition of claim 1 wherein the silicon is deposited on the supportmaterial at a concentration of between about 0.55 Si/nm² and about 5.0Si/nm².
 3. The catalyst composition of claim 1 wherein the silicon isdeposited on the support material at a concentration of between about0.7 Si/nm² and about 3.5 Si/nm².
 4. The catalyst composition of claim 1wherein the support material is selected from the group of gammaalumina, eta alumina, theta alumina, delta alumina, rho alumina, anatasetitania, rutile titania, magnesia, zirconia, refractory oxides of GroupsIII, IV, V, VI and VIII elements and mixtures thereof.
 5. The catalystcomposition of claim 4 wherein the support material is aggregated gammaalumina.
 6. The catalyst composition of claim 4 wherein the supportmaterial is alumina-bound titania.
 7. The catalyst composition of claim1 wherein the catalyst has been regenerated.
 8. The catalyst compositionof claim 1 wherein the support material is preformed.
 9. The catalystcomposition of claim 1 further comprising: between about 12 wt % andabout 30 wt % Co; between about 0.5 wt % and about 2 wt % of a firstadditive selected from the group of Ca, Sc, Ba, La, and Hf; betweenabout 0.03 wt % and about 0.3 wt % of a second additive selected fromthe group of Ru, Rh, Pd, Re, Ir, and Pt.
 10. The catalyst composition ofclaim 1 further comprising: between about 12 wt % and about 30 wt % Co;between about 0.5 wt % and about 2 wt % La; and between about 0.03 wt %and about 0.3 wt % Ru.
 11. catalyst composition comprising: a supportmaterial having between about 0.1 Si/nm² support surface area and about10.6 Si/nm² support surface area deposited thereon wherein less thanabout 10 wt % of the silicon is in polymeric form.
 12. The catalystcomposition of claim 11 wherein the silicon is deposited on the supportmaterial at a concentration of between about 0.55 Si/nm² and about 5.0Si/nm².
 13. The catalyst composition of claim 11 wherein the silicon isdeposited on the support material at a concentration of between about0.7 Si/nm² and about 3.5 Si/nm².
 14. The catalyst composition of claim11 wherein the support material is selected from the group of gammaalumina, eta alumina, theta alumina, delta alumina, rho alumina, anatasetitania, rutile titania, magnesia, zirconia, refractory oxides of GroupsIII, IV, V, VI and VIII elements and mixtures thereof.
 15. The catalystcomposition of claim 14 wherein the support material is aggregated gammaalumina.
 16. The catalyst composition of claim 14 wherein the supportmaterial is alumina-bound titania.
 17. The catalyst composition of claim11 wherein less than about 5 wt % of the silicon is present in polymericform.
 18. The catalyst composition of claim 11 wherein less than about2.5 wt % of the silicon is in polymeric form.
 19. The catalystcomposition of claim 11 wherein the catalyst has been regenerated. 20.The catalyst composition of claim 11 wherein the support material ispreformed.
 21. The catalyst composition of claim 11 further comprising:between about 12 wt % and about 30 wt % Co; between about 0.5 wt % andabout 2 wt % of a first additive selected from the group of Ca, Sc, Ba,La, and Hf; between about 0.03 wt % and about 0.3 wt % of a secondadditive selected from the group of Ru, Rh, Pd, Re, Ir, and Pt.
 22. Thecatalyst composition of claim 11 further comprising: between about 12 wt% and about 30 wt % Co; between about 0.5 wt % and about 2 wt % La; andbetween about 0.03 wt % and about 0.3 wt % of Ru.
 23. A method oftreating a catalyst support, comprising: contacting a support materialwith an attrition-suppressing composition comprising monosilicic acidthereby to provide a treated catalyst support.
 24. The method accordingto claim 23 wherein the treated catalyst support has a surfaceconcentration of between about 0.1 and about 10.60 Si atoms/nm².
 25. Themethod according to claim 23, wherein the attrition-suppressingcomposition comprises between about 0.02% and about 6.9% by weight ofSi.
 26. The method according to claim 23 wherein theattrition-suppressing composition comprises between about 0.2% and about6.9% by weight of Si.
 27. The method according to claim 23 wherein theattrition-suppressing composition is prepared by contacting a silicatewith water under acidic conditions.
 28. The method according to claim 27wherein the silicate comprises monosilicic acid.
 29. The methodaccording to claim 28 wherein the monosilicic acid is prepared bycontacting tetraethoxysilane with water under acidic conditions.
 30. Themethod according to claim 27, wherein the silicate is sodiumorthosilicate or sodium metasilicate and the pH ranges from about 1.5 toabout 3.5 at a temperature ranging from about 0° C. to about 5° C. 31.The method according to claim 27 wherein the attrition-suppressingcomposition is added to the catalyst support at a temperature rangingfrom about 0° C. to about 95° C.
 32. The method according to claim 27wherein the temperature ranges from about 0° C. to about 10° C.
 33. Themethod according to claim 27, wherein the attrition-suppressingcomposition comprises a polysilicic acid species wherein concentrationof monosilicic acid is greater than the concentration of trisilicic acidand higher polymers of the silicic acid.
 34. The method according toclaim 28 wherein the monosilicic acid is the predominant silicic acidspecies in the attrition-suppressing composition.
 35. The method ofclaim 23 wherein the support material is preformed.
 36. A catalystcomposition suitable for use in a Fischer-Tropsch process, comprising amixture or reaction product of: an attrition-resistant support preparedby contacting a support material with an attrition-suppressingcomposition comprising monosilicic acid; cobalt; a modifier selectedfrom the group of Ca, Sc, Ba, La, Hf, and combinations thereof; and atleast one activator selected from the group of Ru, Rh, Pd, Re, Ir, Pt,and combinations thereof.
 37. The catalyst composition according toclaim 36, wherein the composition is substantially free of particleshaving a diameter of less than about 20 μm under typical Fischer-Tropschreaction conditions.
 38. The catalyst composition according to claim 36,wherein the support material is selected from the group of Group III,IV, V, VI, VIII refractory oxides, and mixtures thereof.
 39. Thecatalyst composition according to claim 36, wherein the support materialcomprises aggregated gamma alumina.
 40. The catalyst compositionaccording to claim 36 wherein the first transition metal is cobalt andthe second is ruthenium.
 41. The catalyst composition of claim 36wherein the support material is preformed.
 42. A Fischer-Tropschproduct, comprising: a paraffinic wax; and less than about 50 ppm ofgamma alumina particles having a diameter of less than about 20 μm;wherein the concentration of gamma alumina particles is determinedfollowing primary filtration.
 43. The Fischer-Tropsch product of claim42 wherein the Fischer-Tropsch product is produced using a regeneratedFischer-Tropsch catalyst.